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Full text of "How to fight the chinch bug"

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HOW TO FICHT TH€ 

CHINCH BUG 











BULLETIN 

l\o. 1780 

U.S. DEPARTMENT o/AGRICULTUR 






I 









THE CHINCH BUG is one of the most destructive 
native pests of grain and grass crops in the United 
States. The worst outbreaks occur in the great grain- 
raising region extending from Ohio to Oklahoma. 
Kansas, and Nebraska, but heavy losses also occur in 
the eastern and southeastern sections of the country. 
As far as is known, this insect feeds only on plants 
belonging to the grass family. 

The chinch bug has two generations a year, and 
three in the extreme southern portion of its range. 
When full grown it is black with white markings, and 
is about one-sixth of an inch long. 

The few natural enemies of this insect are not suffi- 
cient to prevent it from injuring crops, and spraying 
and dusting are too expensive to be recommended 
for general use. 

The chinch bug can be fought most effectively (1) 
by growing immune or resistant crops or crop mix- 
tures, (2) by modifying farm practices to prevent 
infestation, and (3) by the use of barrier traps to kill 
the bugs while they are migrating from small grains 
to corn or other susceptible crops. 

This bulletin supersedes Farmers' Bulletin 1 198, 
The Chinch Bug and How to Fight It. 



Washington, I). ( lUHCd Anuu^t US' 



HOW TO FIGHT THE CHINCH BUG 

By C. M. Packard, .senior entomologist, and. Cubtm Benton, junior entomologist, 
Division of Cereal and Forage Insert Investigations, Bureau of Entomology 
and Plant Quarantine 1 



CONTENTS 



Page 

Occurrence and importance 1 

What the chinch bug looks like 2 

Seasonal history 2 

How and where chinch bugs pass the 

winter 2 

The spring flight 3 

Development and migration of first gener- 
ation 4 

The summer flight and development of 

later generations 5 

The fall flight to winter quarters 5 

Life stages 5 



Page 

Plants attacked 7 

Plants not injured 7 

Importance of weather in chinch bug abun- 
dance Js 

Natural enemies__ 9 

Control measures.. 9 

Growing immune or resistant crops 10 

Modifying farm practices to reduce infes- 
tation 11 

Barriers 13 

Spraying and dusting with insecticides as 

emergency measures 20 



OCCURRENCE AND IMPORTANCE 



THE CHIXCH BUG is one of the most destructive of the native 
insects attacking grain and grass crops in the United States. 
It is of some importance in the southeastern and eastern sections of 
the country, but lias reached its greatest abundance in the regions 
drained by the Mississippi, Ohio, and Missouri Rivers. 

A knowledge of the best methods of controlling this insect has been 
sought by grain growers since its first general outbreak, which oc- 
curred about 1785. During the intervening L50 years there have 
been numerous chinch bug outbreaks, in some instances covering only 
parts of one or two States, but in others extending over a much 
wider area. The chinch bun's habit of feeding on the widely grown 
grains and grasses, its rapid rate of reproduction under favorable 
conditions, and its frequent occurrence in enormous numbers make 
it an extremely difficult pesl to fight. The general use of insecticidal 
sprays is impractical, because chinch bugs feed by sucking the plant 
juices, and only poisons that kill by actual contact with the insect 
are effective. Qther means of combating them must therefore be 
sought. 



1 Acknowledgment i* duo to w. r. Flint, «',. n. Dnngan, and J. II. Bigger for Informa- 
tion taken from Illinois Agricultural Experiment station Circular 131 : to C. J. 
G. »'. Decker, and A. I> Worthington for Information and li^s. :> and in taken from Iowa 
Agricultural Extension Service Circular 213; and to Ralph O. Snelling for observations 
on iii.' third generation in Oklahoma (Jour. Econ. lint. 29: ."7 803, lllus. 1936). The 
photograph reproduced on the iiil«' page Is used by courtesy of .1 J. Davis, of the Indiana 
Agricultural Experiment station, and tin- photograph used for fig 7 «;i- mad. bj M I ». 
Parrar, ot the Illinois Natural Hist on Survey. Material from Fanners' Bulletin 1498, 
The Chinch Bug ami How to Fight ii, has been fre< 



2 FARMERS' BULLETIN 1780 

WHAT THE CHINCH BUG LOOKS LIKE 

The full-grown chinch bug (Blisisw leucopterus Say) is a black 
insect with white markings, not over one-sixth of nn inch long (figs. 

I and 5, G). Both long-winged and short-winged forms are found. 
but the long-winged form prevails throughout the Central States. 

I I is capable of flying considerable distances, probably as far as 10 
miles in a single flight when the wind is favorable. The short- 
winged individuals are unable to fly. In the East and North a some- 
what more hairy species {Blissus hirtvs Montd.) also occurs, espe- 
cially in lawns and grassy areas. Short -winged individuals are usu- 
ally more prevalent in that species. 



~ * 



:-• 



Figure l. — Chinch bags, twice natural size. 
SEASONAL HISTORY 

Ordinarily there are two generations of the chinch bug each year 
throughout its entire range in this country, with a third generation 
in the extreme South, and occasionally a partial third generation 
farther north. 

HOW AND WHERE CHINCH BUGS PASS THE WINTER 

Chinch bugs pass the winter in the adult Stage, hidden away in 
shelters that afford them good protection from I he weather. They 
prefer to hide deep down in the tufts of the clump-forming native 
grasses (fig. *2). These grasses are known locally as bunch grass, 
bluestem, prairie grass. broomgraSS, swale grass, beardgrass, and by 
several other name.-. The bugs also hibernate in clump-forming 
grasses, such as timothy, purpletop, orchard grass, dropseed, and 
sedge-, especially where the. so-called bunch grasses do not occur. 
Many bugs pass the winter under leaves and litter in the borders of 
woodland- and under hedges. Leaves or litter containing some grass 
(fig. 3) are preferred to either of these materials alone. From No- 
vember to April the most likely places to find chinch (mil's are the 
types of cover jusl described, especially on warm southern and 

western exposures where the sun shone during the afternoons of the 

preceding September and October when they were seeking winter 
quart 

Chinch bugs may sometimes be found under the leaves of mullein 
or other weeds thai form rosettes of large leaves at the surfaci 

the ground, under the bark of dead trees and fence posts, under 



HOW TO FIGHT THE CHINCH BUG 



boards and logs, in shocks of corn or standing cornstalks, in sor- 
ghum stubble, or under the loose boards and shingles of houses, in 
sheds and outbuildings, and in various other shelters. The percent- 
age passing the winter in all such places, however, is small, and many 
of the bugs die. 




Piocbi 2. — Bunchy perennial grasses like this are preferred by chinch bugs for win: 

THE SPRING FLIGHT 



The spring flights of overwintering bugs occur some time between 
February or March and the Last pan of May, depending on the sea- 
son, on sunny days when for several hours the temperature remains 
at 70° F. or more, and usually only after 1 or 2 sucn days. In most 
years the flight is gradual, but sometimes nearly all the chinch bugs 
in a locality leave their winter shelters during 2 or 3 davs of favor- 



4 



FARMERS' BULLETIN 1780 



able weather. They usually settle in fields of small grain, especially 
in the thinner or poorer stands. The greater number of the bugs 
locate in wheat where that is the predominating small-grain crop, 

but they may often be found more abundant in rye or barley, where 
these grains are growing. In certain years, when oats have been 
planted early and cool weather has delayed the flight until the oats 
have made a good growth, many of the bugs may also settle in this 
crop. In such years a few of them may even fly direct to young corn 
Once in the fields of small grain, the bugs spend a few days feed- 
ing and mating before vts^, laying begins. Ordinarily tittle or no 
injury to the small grains is apparent as a result of their feeding, 
but in years of drought and heavy infestation they may seriously 
injure or even kill the small grains in which they settle. When con- 
ditions become unfavorable for them, either through the drying up 




Figure 3.— Tufts of grass among woodland leaves arc also favored places for hibernation. 

of these grains or because of thick-, rank growth, they often move to 

other fields or portions of fields more to their taste. Occasionally 
serious infestations of oats and corn occur in this way. There IS 
often a considerable flight of the old bugs from the small grains to 
young corn after they have practically finished laying eggs. 'The 
sudden appearance of these spent adults in the cornfields is alarm- 
ing, but needlessly so. since they soon die without doing much feed- 
ing or egg laying on the corn. The real danger at this time is from 
the young bugs lliev left behind them in the small grains. 

DEVELOPMENT AND MIGRATION OF THE FIRST GKNKRATION 

Al'ler I he period of feeding and mating, the females begin to lay 
their eggS. These are deposited behind the lower leaf sheaths of the 
grain plants or in the ground around the plants, and in dry years 
when the ground is clacked they may be laid on the roots. The 

ordinarily hatch in from 1 to 2 weeks. By wheat-harvest. time 

the old bugs are practically all dead, and the young bugs of the new 




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Se/r/7 Mese grasses- trM/e cMy, t'/9u<S' 
A////hy Me days ana' 'sar/ny Me yra//7/ 



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Digitized by the Internet Archive 
in 2013 

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http://archive.org/details/fightchinchOOpack 



HOW TO FIGHT THE CHINCH BUG 5 

generation are present in nearly all stages of growth, although still 
unable to fly. As the small grains ripen or dry up, the young bugs 
begin traveling on foot to find succulent food. They do this mainly 
in the afternoons of sunny days, although in cloudy weather there 
may be some movement throughout the day. At this time they move 
into adjacent fields of young corn, sorghum, or other plants of the 
grass family, where they resume feeding and complete their growth 
to the winged stage. It is during this migration that barrier-trap 
control (see p. 13) is effective. 

THE SUMMER FLIGHT AND DEVELOPMENT OF LATER GENERATIONS 

From 2 weeks to a month after the small grain is harvested there 
is a second flight to seek favorable host plants on which to feed and 
deposit eggs. It is during this flight that the bugs spread throughout 
the corn and sorghum fields, especially to thin stands or poor growth. 
As the summer advances, the adults of the first generation complete 
their egg laying and gradually die off, while the second generation 
hatches from these eggs and feeds mainly on corn, sorghum, foxtail, 
timothy, Sudan grass, and certain other grasses which may be in 
succulent condition during the summer. The second generation 
reaches the full-grown winged stage late in the summer or early 
in the fall. In the extreme South, where activity begins earlier in 
the spring and continues later in the fall, a third generation usually 
develops. Under particularly favorable conditions a partial third 
generation sometimes occurs as far north as Iowa. 

THE FALL FLIGHT TO WINTER QUARTERS 

The third, and last, flight occurs in the fall, when the adults of 
the second and third generations leave their summer food plants and 
seek hibernation quarters. Much of this flight seems to be rather 
gradual, beginning late in August and continuing through October 
and, in the South, even into November. General flights often occur, 
however, during the latter part of this period, particularly on very 
warm, sunny days following a period of frosty weather. The bugs 
seek winter quarters only on days when the sun is shining and while 
the temperature is at least 70° F. 

Once in their winter quarters they became sluggish when the air 
temperature is low. and inactive when it is below freezing, but 
during periods of comparatively high temperature in the winter they 
may move about to a limited extent. Although they may take water, 
they apparently do not i'vvd from the time they seek their winter 
quarters in the fall until they Leave them in the spring. Some mating 

may occur before t he spring flight. The seasonal history of t his insect 
i- summarized graphically in figure l. 

LIFE STAGES 
The female chinch bug lay- Several hundred eggS at the rate of 

i 20 a day: hence from :; to l weeks may lie required for her 
to lay her full quota. The eggs, which are about one thirty-second 

of an inch long (fig. ;>. .1). hatch in from 7 to 45 days, depending 
mainly upon the temperature. A very young bug (tig. .V B) LS about 



6 



FARMERS' BULLETIN 1TS0 




i lie winged ;nluli 



HOW TO FIGHT THE CHINCH BUG 7 

half the size of a pin head, and bright red marked with a transverse 
band of white. In the course of its growth its skin is shed five times, 
and each change gives it a darker coat until, in the last stage before 
acquiring wings, it has lost most of its red color and become grayish 
black with a conspicuous white spot on the back between the wing 
pads. In all these preliminary stages (fig. 5. B-F) the insect is 
wingless and has to depend entirely upon its legs for locomotion. In 
the sixth, or adult, stage the insect has wings, is about one-sixth of 
an inch long, and is black with white markings (fig. 5, G). 

PLANTS ATTACKED 

So far as is known, the chinch bug feeds only on plants belong- 
ing to the grass family. This includes all our small grains, corn. 
broomcorn, the sorghums, millet. Sudan grass, and other wild and 
cultivated grasses. Of the small grains, barley seems to be pre- 
ferred above all others. It has been observed repeatedly that, where 
several kinds of small grains in practically the same stage of devel- 
opment are available to the bugs in the spring, barley is by far the 
most heavily infested. Barley, spring wheat, winter wheat, rye, 
and oats seem to be attacked in about the order named, although this 
order varies from year to year with the condition of the grains at 
the time of the spring flight. Where any one of these grains pie- 
dominates, the chinch bugs readily feed upon it. During April, May. 
and June, after the spring flight, probably 90 percent of the bugs 
are found in the fields of small grains. Where the acreage of small 
grains is relatively low, the bugs may be found on timothy, june- 
grass, and several other wild grasses that appear during these 
months. Occasionally a few bugs occur on bluegrass, but apparently 
this grass is not succulent enough to be attractive, as the chinch bug 
feeds only by sucking, and it must have a food plant with a consid- 
erable flow of sap, as well as with stems that it can pierce readily 
with its beak. 

Throughout the corn-growing sections the second generation of 
chinch bugs depends mainly upon corn for food (fig. 6), although it 
also feeds on other grains and grasses that may be in succulent con- 
dition late in the summer, including timothy, barnyard grass, tickle 
grass, crabgrass, foxtail, and bent and other lawn grass* 

PLANTS NOT INJURED 

Fortunately, the chinch bug does not develop on any member of 
the great family of soil-building crops known as legume-. The 
clovers, alfalfa, vetch, lespedeza, soybeans, cowpeas, field peas, pea- 
nuts, and velvet beans are all immune from chinch-bug injury. Other 
common crops not belonging to the grass family that may be grown 
during period- of chinch-bug abundance with the assurance that they 

will not be damaged are sunflower, flax, rape, stock beet, buck- 
wheat, pumpkin, squash, and all the truck or garden crop- except 
sweet corn. When the bugs are extremely abundant and their nor- 
mal food plant- become very scarce through the combined result of 
t heir ravages and drought, they sometimes t ry to U'vd on legumes and 
certain vegetable crop-. They cannot i'wd successfully on these 
plants, however, and only rarely do they attempt to do so in numbers 

It II -2 



8 



FARMERS' BULLETIN 1780 



large enough to cause any injury The substitution of legumes and 
other immune crops for small grains and corn offers one of the most 
important and valuable mays of avoiding or overcoming trouble elue 
to chinch bugs. 

IMPORTANCE OF WEATHER IN CHINCH BUG ABUNDANCE 

The weather is the chief factor governing the abundance of chinch 
bugs. They are most susceptible to weather conditions while they 
are hatching. The hatching period of the first generation extends 
from April to about the middle of June, and that of the second gen- 
eration from the middle of July to the middle of September, with 




Figure 6. — Corn damaged by Invasion of chinch bugs from adjacenl small grain. This 
could have been prevented by limely use <>i ;i good barrier or by not planting corn and 
small grain in adjoining fields. 

some variation according to the latitude. Frequent heavy, driving 
rains during these periods heat the young bugs into the mud, from 
which they arc unable to escape. Such storms also cover the eggs 
with mud and prevent them from hatching, and keep the females 
from laying their full number of eggs. A- a result the bugs may 
be of little importance as farm pests for several seasons. Frequent 

jains or periods of warm, damp weather also favor the development 

of the chinch bugs' worst natural enemy, the white-fungus disease. 
Chinch bugs are less able to survive an open, wet winter than a 

cold one wit h heavy snow cover. Many bugs are also killed l>y sudden 
changes in temperature, extremely low temperatures while there i> 
little snow cover, or the formation of ice in their hibernation char- 
ters due to a sudden U^^av following a thaw or rain. In the Middle 
. however, less than in percent of the bugs die in a normal 
winter. 

All the recorded outbreaks of the chinch bug have begun during 
periods of normal or less than normal rainfall, and it has usually 



HOW TO FIGHT THE CHINCH BUG 9 

been several years before adverse weather and other natural condi- 
tions were able to reduce the number of bugs to the point where they 
became unimportant. One of the most persistent outbreaks orig- 
inated in 1910 in Illinois, Missouri, and Kansas, and, except in 1915, 
when an extremely wet summer greatly reduced their number, losses 
occurred every year until 1925. Again in 1930 lack of rainfall dur- 
ing the breeding season allowed increases in chinch bug abundance 
which culminated in 1934 in the most severe and widespread out- 
break ever known. Populations were greatly reduced in 1935, lo- 
cally by winter mortality but mainly by the widespread cold, rainy 
weather in May and June, which delayed the spring flight, reduced 
egg laying, and destroyed many bugs of the first generation as they 
hatched. Shortage of rainfall, however, during the remainder of the 
season, and again in 1936. favored chinch bug increase, until at the 
end of 193G threatening numbers were again present in several Mid- 
western States. 

NATURAL ENEMIES 

Probably the most destructive natural enemy of the chinch bug is 
the white-fungus disease (Beauveria globulifera). It is generally 
present in the fields throughout the country, but its effectiveness is 
dependent on the weather. Since it has been proved that the spores 
of this fungus are present wherever the bugs are common, its artifi- 
cial dissemination as a control measure is needless. 

Next in importance is a tiny wasplike parasitic insect (Ewm&cro- 
soma benefica Gahan). This little wasp lays an egg in the chinch 
bug egg. The maggot hatching from the was]) egg consumes the 
contents and develops inside the chinch bug egg, and when this 
maggot becomes full grown it changes to the adult wasp, which 
emerges from that egg instead of a chinch bug. This beneficial 
insect is so small that it is probably never seen by farmers. When 
held in the palm of the hand, it appears to be merely a dark speck, 
and only microscopic examination reveals it as an insect ; yet rec- 
ords show that it has parasitized from 30 to 50 percent of the chinch 
bug eggs in certain localities. Such a high percentage of parasiti- 
zation is unusual, however. It is known to occur over most of the 
States of the Middle West and in one Eastern State, but has not 
been taken in the far West . 

Several other fungus diseases and insects also attack the chinch 
bug; and a number of birds, including the bobwhite, the red-winged 
blackbird, the catbird, the brown thrasher, and the meadow lark, are 
known to feed on it. More than 200 chinch bugs were found in the 
stomach of a single brown thrasher and more than 100 each in the 
stomachs of a bobwhite and a meadowlark. Many other hi ids have 
taken from .""> to 50 chinch bugs at a single meal. None of these, 
however, appear to he important factors in its control more than to 
aid other natural enemies in preventing serious outbreaks. 

CONTROL MEASURES 

There is so much uncertainty about the duration of chinch bug 
outbreaks that it is never safe for the grain grower to depend upon 

natural agencies to curb losses from them. various method- of con- 



IQ FARMERS 1 BULLETIN 1780 

trol, including spraying and dusting, have been tried, but there are 
only three measures that have proved generally practical. The 
following methods can be used effectively under actual farm condi- 
tions, as will be explained, and by their use losses due to chinch 
bugs can be materially reduced: (1) Growing immune or resistant 
(tops or crop mixtures, (2) modifying farm practices to prevent 
infestation, and (3) using barrier traps to kill the bugs while they 
are migrating from small grains to corn or other susceptible crops. 

GROWING IMMUNE OR RESISTANT CROPS 

Since the first-generation bugs depend mainly on small grains for 
their food, and those of the second generation feed mostly on corn 
and sorghum, a good way to hold this insect in check is to make its 
food supply as scarce as possible. This can be done by reducing 
the acreage of small grains where corn and sorghum are the leading 
crops, and that of corn and sorghum where small grains predomi- 
nate, and planting legumes or other immune crops in their place. 
In this way one of the generations of bugs will be severely handi- 
capped. 

For a farm especially well adapted to corn production, a rotation 
of corn, soybeans, corn, oats, or wheat and clover will result in as 
little loss as any that includes both small grain and corn. With this 
rotation corn would occupy about 40 percent and the other crops 
each about 20 percent of the cropped land each year. In areas 
better suited to the production of small grains a rotation may be 
used in which wheat or oats, clover, corn, and soybeans each occupies 
about 2~> percent of the cropped land each year. The most suitable 
rotation for any particular farm where the chinch bug i> a problem, 
however, can best be ascertained from the county agent or State 
agricultural experiment station. 

Legumes should not only be grown by themselves, but where prac- 
tical they may well be planted among small grains and corn. Ap- 
parently there is nothing about these crops that is repellent to chinch 
bugs, since they will alight upon and crawl over or through them. 
ana may even try to feed on them when forced to it by extreme 
starvation. Legumes are practically immune from chinch bug in- 
jury, however, and the growing of the clovers, alfalfa, or vetch 
among small grains and of soybeans or cowpeas among corn often 
helps to produce a condition of shade and dampness around the 
lower parts of the grain plants that i> unfavorable to thi 4 bugs anil 
oided by them. 

Experiments in growing corn with and without soybeans or cow- 
peas have shown that considerable protection is afforded the corn 
by these Legumes. In the presence of chinch bug infestations corn 
grown with soybeans or cowpeas has outyielded corn grown without 

these Legumes by from '1 to IT) bushels per acre. The degree of 

benefit depends on the number of chinch bugs present , the fertility of 

the soil, and the weather. In extremely (\v\ weather, with a heavy 

infestation of chinch bugs, the beneficial effect of the Legumes may 

not be great, and possibly the bugs may destroy all the corn in 

the field. Even under such conditions, when planted at the pate of 
three beans per hill of corn, the soybeans themselves have yielded 

from 10 to \'l bushels per acre, ruder nearly all conditions they 



HOW TO FIGHT THE CHINCH BUG \\ 

may be expected to make sufficient growth to afford good pasturage 

for hogs, sheep, and cattle, and to give at least a partial crop on the 
land. 

It has been found that certain strains or varieties of corn and 
sorghum are decidedly resistant to the attacks of the second-genera- 
tion bugs, although they need protection from the first generation. 
Certain types of sorghums, however, particularly the milos, Honey 
sorgo, and Bishop kafir, are so susceptible to chinch bug injury that 
they are not ordinarily grown where chinch bugs are prevalent. In 
southern Illinois the corn varieties Black Hawk, Champion White 
Pearl (sometimes called Democrat), Golden Beauty. Mohawk. Wad- 
dell Utility white dent, and Waddell Utility yellow dent have made 
fair yields under heavy infestations which so badly damaged other 
varieties grown in the same field that they produced very little grain. 
None of these varieties, however, is chinch bug proof. Practically 
as many bugs occur on the resistant as on the nonresistant varieties 
of corn. As these varieties require a long growing season, they are 
not suitable for more northern locations. 

In recent years much progress has been made in Illinois, Kansas, 
and Oklahoma with the development of hybrid corns and sorghums 
distinctly resistant to second-generation chinch bugs. These results 
open up the possibility of finding resistant varieties ami hybrids 
adapted to other regions as well. The best of these hybrids are 
much more resistant than the open-pollinated varieties. When 
of resistant hybrids is available, it should be ttsed in preference to 
resistant varieties. Some hybrids, however, are decidedly sus- 
ceptible to chinch bug injury and should be avoided. When seed of 
resistant hybrid corn adapted to any particular locality is not avail- 
able, it is recommended that the highest yielding hybrids or open- 
pollinated varieties known to be suited to that locality be grown in 
preference to untried resistant corns brought in from some other 
seel ion. For information concerning the besl resistant varieti 
corn or sorghum for your locality, consult your county agent or 
State experiment stat ion. 

MODIFYING FARM PRACTICES TO REDUCE INFESTATION 

When it is not practical to eliminate or even to reduce materially 

the acreage of small grains on farms where the chinch bug i> a prob- 
lem, it becomes necessary to take other measures to reduce ink 

I ions in 1 hese grains. 

The first measure is the selection of the kind to plant, where a 
choice can be made. Chinch bugs will feed and breed abundantly 
in any of the small grains under the right conditions: hence none 
of them can be depended upon for use as a trap crop in which t hi' 

bugs may !-<■ effectively concentrated and destroyed. The compara- 
tive attractiveness of the -mall grains varies with the condition of 
the grains in different years or areas, but it is usually in about the 
following order: Barley, spring wheat, winter wheat, rye. and oats. 
The planting of spring barley should especially be avoided when 
there is a prospect of chinch bug abundance, and. where feasible, 
the other small-grain plantings should be adjusted to reduce the 
acreages of w heal and rye and make use of oats instead. 



12 FAKMKKS' BULLETIN 1TSU 

In the more southern areas, such as central and southern Missouri, 
winter barley sown early in the fall produces in the spring a thick 
growth that is less attractive to chinch bugs than spring-sown barley. 
Furthermore, the winter barley matures so early that it can be har- 
vested before the first-generation bugs have injured it materially 
or have had opportunity to make much growth. The barley can be 
used awhile for spring pasture, or harvested for grain, and the 
ground then plowed tip for replanting to soybeans the same season, 
the bugs being destroyed in the process before they are able to 
migrate to other crops. In some of these areas the advantages to 
be gained through the use of winter barley sown early in the fall for 
pasture appear to outweigh the objection to this crop on account of 
us attractiveness to chinch bugs. 

Another helpful measure is the stimulation of a thick, vigorous 
growth of grain. Chinch bugs seldom congregate or breed in heavy 
stands of any small grain; hence anything that can be done to pro- 
duce this condition, such as thorough tillage, ample fertilization, and 
timely seeding, helps to reduce injury from the bugs. Even winter 
wheat can be planted with fair assurance that chinch bugs will not 
breed in it abundantly, provided a thick, vigorous spring growth can 
be obtained. A dense growth of clover in small grain also helps to 
bring about a damp, shady condition that is unfavorable to the 
bugs. 

In dry seasons when there are severe infestations, ruined fields of 
small grain can sometimes be disked or plowed up to advantage to 
destroy the bugs, and replanted with soybeans or some other immune 
crop. Before such a field is plowed, a dust barrier, as described 
later, should be prepared to prevent migration of the bugs into adja- 
cent grain or grass fields. Immediately after being plowed, the en- 
tire field should be thoroughly cultivated to destroy all green growth 
and to product 4 a good dust mulch. By these means the bugs usually 
can be starved to death or otherwise killed and are thus no longer 
a menace to the succeeding or adjacent crops. Corn or a quick- 
growing grass crop can be planted after such treatment, provided 
the dusl mulch has been maintained until all eggs have hatched and 
the bugs in the field have all been killed. 

Where migrating bugs have ruined young corn, it is often possible 
to disk the ground and replant to soybeans, thus securing a worth- 
while crop from the land even though the original crop of corn 
is lost. Injury to corn and sorghums can be partly evaded by early 
planting. 

Still another way of reducing chinch bug damage is to adjust the 

cropping system so as to avoid adjacent plantings of small grain and 

<-orn. Where this is not possible, plans should be made t<> run a 

ote barrier between the plantings if necessary, and just before 

harvest tunc close watch should be kept for chinch bugs in the small 

grains to determine whether or not migration to corn may be ex- 
pected. Neighbors can often cooperate to advantage by arranging 
to plant corn in adjoining fields, or otherwise to avoid the growing 

of -mall grain and corn adjacent to each other. 

In the more western regions, where the native bunch grasses form 
i he principal shelter, burning over the most favored hibernation 

quarters while the bugs are in them, some time between November 



HOW TO FIGHT THE CHI.XCH BUG 



13 



1 and March 15, may help to reduce their numbers. On the other 
hand, in regions where the bunch grasses are uncommon and many 
of the bugs hibernate in other types of shelter, winter burning is 
not a practical or effective method of control. Woodlands should 
never be burned over, because the harm resulting from destruction 
of the young growth and wildlife refuges will more than offset the 
benefit. The natural bird shelters in tmwooded areas also should be 
left unburned or, if burned, should be replaced by a few brush piles 
or corn shocks. An additional objection to the burning over of 
grasslands is that it increases the danger of erosion. Because of the 
injury to the stand and the reduction in growth the following sum- 
mer, permanent pastures and hayfields should not be burned. The 
burning of small-grain stubble and cornstalks is not warranted, be- 




rall&'-' 



7. corn at left ruined l>.\ invasion of chinch bugs from adjacenl small grain; rhat 
<mi the right saved by a creosote barrier. (Illinois State Natural Historj Sun 



cause very few bugs winter over successfully in such cover. All 
things considered, indiscriminate and wholesale burning is likely to 

do more harm than (JOOd. 

BARRIERS 

One of the oldest and best methods for controlling chinch bugs 
is the use, at harvest time, of barriers along which the young bugs 
can be killed as they crawl from the ripening small-grain fields into 

corn or into small grains that may still be green. As chinch bug- are 
dependent on succulent plants lor food, they are compelled to leave 
t he small grain w hen it ripens and k\y'w> or is cut. At this time only 
a few bugs have reached the full-grown, or winged, stage, and most 

of them have to migrate on foot. By the timely construction and 
maintenance of barriers it i> possible to prevent most of the damage 
done to coin or previously uninfected small grain by the bugs 

migrating to it on foot (fig, 7). and also to reduce the damage i<> 



14 FARMERS' BULLETIN 1780 

corn by their progeny later in the summer. The saving of only 1 
acre of corn more than repays the cost of 80 rods of barrier. In 
one instance 8 bushels of bugs were caught along half a mile of 
creosote barrier in a week, and approximately the same quantity 
in the same field the next week. By counts of single quarts ol 
chinch bugs it was estimated that at least 60 million chinch bugs 
were caught along this line in 1 week. 

Barriers are not effective in controlling the bugs after they have 
acquired wings. In the more southern areas the bugs may be winged 
before they leave the small grains, thus rendering the barriers totally 
ineffective. 

MATERIALS USED 

Many kinds of barriers have been tried, and several have been 
found effective. Field tests have shown that oils with a fairly light 
body are most easily applied, soak into soil or paper readily, and. 
unless applied too heavily, do not run down at right angles to the 
line and thus reduce the efficiency of the barrier. Heavy oils lose 
their effectiveness sooner through loss of odor, hardening, or drying. 
and becoming covered with dust. 

Coal-tar creosote has been used extensively for a number of years, 
and this material is the best of any thus far tested. Coal-tar creo- 
sote, Federal Specification TT-W-556, 2 is recommended above all 
others because of its repellent and lasting qualities, low viscosity, 
ready availability in large quantities, and low price. Coal-tar creo- 
sote and its fumes hare a caustic effect on the skin, and this ma- 
terial is also poisonous when taken internally. These facts should 
be kept in mind when working with this material, and close contact 
with it should be avoided as much as possible. Coating the hands 
and face with petrolatum or cup grease helps to prevent creosote 
burns. 

Other materials have been found effective in the following order: 
Naphthalene drain oil. gas tar. pine-tar oil. and wood creosote. Any 
of these that have a strong odor of naphthalene, creosote, or phenol 
can be used to good effect if it can be purchased cheaply. 

THE DIKI-Hlix.l CREOSOTE BABBIEB 

The foundation for a creosote barrier is best made by throwing 
ii]) a ridge <>f earth with a plow, turning the dirt toward the corn. 
A disk cultivator Or small road grader may be used instead of a plow 

if more convenient. The side of the ridge toward the hugs should 

be smoothed and packed with a section of a harrow or a narrow drag 
so thai it is free from clods, cracks, or trash, [f necessary, the upper 
pari of the ridge should he firmed with a shovel. A line of creosote 
is then applied. as shown in figure S. along the brow of the ridge 
hut not quite on top of it. so that the bug- are -till climbing upward 
when they reach it but are not yet at the top where they are likely 
to he blown across the line by the wind. If the line i< placed either 
in the bottom of the furrow or on the top of the ridge, the foremosl 



in coal-tar are usually familiar with these specifications. If not, ;i 

copy of them may be obtained from the Superintend) cuments, Washington, D.«€ 

i'i ice •". cents. 



HOW TO FIGHT THE CHINCH BUG 



15 



bugs are likely to be pushed across by those crowding up behind 
them. 

A convenient container to use for applying the creosote is a tin 
or galvanized bucket in the side of which a hole has been punched 
with an eightpenny nail. The hole should be about 1 inch from 
the bottom so that it is not readily clogged, and should be directly 
below the point where the bail is attached. The creosote is allowed 
to run from this hole as the bucket is carried along the barrier. A 
line one-half inch wide is just as effective as one 2 or 3 inches wide. 
Therefore, only a small quantity is necessary for one application. 
Fresh creosote should be applied to the original line at least once 
a day for the first few days; after this, if care has been taken to 
follow the same line each time, it need be renewed only once every 
2 or 3 da vs. unless the weather is extremely hot and dry. 




/77/yr<7f/o/7 ~*~ 



r*-'/ = b&£/0/£ fcap 



Figure 8. — A dirt-ridge creosote barrier. Very efficient if creosote line and post-bole traps 
are properly constructed and maintained. 

When poured on the ground the creosote sinks in immediately, 
making a brownish line on the surface, and giving off a strong odor 
that is very repellent to the bugs. This repellent odor seems to be 
all that keeps them from crossing the line, and if it has been prop- 
erly Located rery lVw actually do so. Light rains have the effect of 
freshening the creosote, as it i> oily and comes to the surface when 
the ground is wet. When properly applied, 50 gallons of creosote 
will maintain a quarter <>f a mile <>f barrier for about :> weeks, which 
ordinarily i^ Longer than the barrier is required. 

Post holes for trapping the bugs should be dug in the furrow from 
1 to 1 rods apart and from L8 to -JO inches deep. The more numerous 
the bugs, the closer should be the holes. They should be set part. 
way into the ridge, and their rims should be steeply flared all 
around with the slope extended well up toward the creosote line. 



IQ FARMERS' BULLETIN 1780 

The Mared ring should also be kept covered with fine dust. The 
bugs traveling toward the cornfield encounter the creosote line. 
begin moving along it in an attempt to find a crossing, lose their 
footing in the loose dust, and tumble into the post holes. Few of 
them can crawl out if the rims of the holes are kept dusty. Trapping 
the bugs in the post holes and destroying them is fully as important, 
as stopping their migration. This feature of barrier operation is 
too often neglected. 

After completion this type of barrier should not be dragged, and 
it should be kept in good repair. The efficiency of the post-hole 
traps must be maintained continuously by means of fresh dust 
around their rims when needed. If dust is not available from the 
dirt floor of a barn or shed, a bushel or so should be stored away 
for use in case rain spoils that usually available in the field. 

The bugs trapped in the holes should be killed every afternoon 
at about sundown. An easy way of doing this is to sprinkle 1 or 2 
tablespoonfuls of kerosene into each hole. Do not ignite the kero- 
sene, but let the bugs work it around among themselves. 

THE OREOSOTE-TREATED PAPER-FENCK BARRIER 

A paper-fence barrier has been developed and rather widely used 
in Iowa and Illinois. It is made by setting upright in the ground 
;i strip of creosote-soaked paper about 4 inches wide, with half its 
width above the surface (fig. 9). Experience has shown that the, 
4-inch width is the best for practical use. and that the strip is most 
effective when placed 2 inches below and 2 inches above the ground. 
This 2-inch fence of creosoted paper acts as a physical as well a- a 
chemical barrier and prevents the bugs from being blown across the 
line by wind or crowded across by their fellows. It also helps to 
avoid bridging of the line by straws, leaves, or dust : breaks in the 
barrier due to cracking of the soil in dry weather: and injury to 
the soil by the creosote. Although the treated paper fence is installed 
with more difficulty than the creosote line applied directly on the 
-oil. it is less troublesome and expensive to maintain effectively in 
all kinds of soil and weather when properly made with paper of 
the right kind. Paper fences can be installed either on the usual 
type of furrow and ridge described and illustrated above or on 
clean, level ground a- shown in figure !). Where the hairier i< 

likely to be submerged by the accumulation of rain water in low 
^pots. its location on a ridge is preferable. After the paper has 
been prepared, two men can build 80 rods of paper fence in aboiu 
•} hours. 

Single-faced corrugated paper, tarred (nol asphalt-treated) felt 
paper of the 11- or L 5 -pound grade, red-rosin building paper of 

I lie 30-pound grade or heavier, and heavy chip board or chip straw- 
hoard ranging from 20 to 40 points in thickness have been used 
successfully. The choice of paper is usually determined by avail 
ability and' cost. The rolls as purchased are nrsl cut with a crosscut 
-aw into narrower rolls about 4 inches wide. With some papers it 
i< necessary to oil the saw blade or clean it occasionally with kero- 
sene. After being cut. the rolls should be soaked for at leasl 12 
hour-, in a container with enough creosote to keep them covered. 



HOW TO FIGHT THE CHINCH BUG 



17 



They should then be allowed to drain for an hour or more before 
the fence is built. 

The manner of erecting the treated paper fence depends upon the 
tools available and the character of the soil. A handy tool for use 
in unrolling and installing the paper strips may be made by fitting 
a broom handle into a hole in the side of a piece of *2 by 4 about 
a foot long, bu as to form a T-shaped carrier, and slipping the roll 
of paper down over the handle until it rests on the crosspiece at 
the bottom. After a ridge or a smooth path free from litter has 
been prepared, a wheel hoe or a garden cultivator with a small 
plow attachment, or a corn cultivator with all but one shovel re- 
moved, may be used to open a small furrow to receive the paper. 




- 

*j)iall<jram field 
mo/ chit id i 



*^~T, -Post hole 



bun miq ration 
v , " [\ Paper fence 

•..•;., •"/-. - ■ ■.•"•■ 



Figure !>. — Creosote-treated paper-fence barrier, a recent Improvement over the creosote 

ground-line type. (Iowa State Agricultural Experiment station.) 

When the ground is very hard, it may bo necessary to use a turnplow. 
In this case the paper is unrolled against the straight, or land, side 
of the furrow and the dirt is packed against it. In any event it is 
important that the dirt be packed firmly and evenly to the same 
level on both sides of the paper, for if it is left higher on one side 
than on the other, rain water or caving soil may cause greater pres- 
sure on the higher side, resulting in a collapse of the fence. 

i holes for trapping and killing the bugs are jusl as important 
with paper fence.- as with the ground-line creosote barriers. They 
should be dug every 1 to i pods on the side of the paper toward the 
small grain and from } to 6 inches away from it. with their edges 
-loped out almost to the paper and then dusted. 

The paper fence should repel the bug- for 2 or •'> days, if it has 
been properly treated. Then it will have to he freshened by applying 
more creosote close to the top edge of the paper. A bucket with a 



18 



FARMERS' BULLETIN 1780 



hole near the bottom as described on page 15 can be used for this 
purpose, but the application can be made much more easily if a cop- 
per tube is soldered into the hole so as to extend downward for 12 
or 15 inches, its end being curved sideways to direct the stream 
against the paper. A horizontal prong is soldered to it close to the 
lower end to slide along the top edge of the paper and act as a guide 
(rig. 10). A single treatment of one-fourth mile of 2-inch paper 
fence requires 2 or 3 gallons of creosote. After it is well soaked, 
the paper barrier will not need retreatment so frequently as a creo- 
sote line on the ground. 

The treated paper barrier costs about the same as the dirt-ridge 
ground-line creosote barrier. About 30 gallons of creosote Avill ordi- 
narily be sufficient to maintain 
a quarter of a mile of paper- 
fence barrier for the season. 
This is about two-thirds the 
quantity required for the 
ground-line type. Enough 
paper for a quarter-mile of 4- 
inch strips costs approximately 
$2. With creosote at 20 cents 
a gallon, the cost of paper bar- 
rier would thus be $6 for the 
creosote plus $2 for the paper. 
or a total of $8 per quarter 
mile. 

< KKOSOII -I HI All I) BOPE 1 I N( I 

Another type of creosote bar- 
rier that found some favor in 
Ohio in 1935 is made by using. 
instead of the paper strip, a 
special kind of soft rope about 
one-half inch in diameter. A 
smooth, well-packed path is 
first made along the side of the 
field to be protected. The rope 
IS then laid in place on this 
path, and one end is threaded through a specially designed ere 
applicator, which consists of a bucket containing a fixture bearing 

spools to guide the rope down into the creosote and out again on the 
other side of the bucket. The end of the rope is then fastened to a 

stake, and the applicator is carried along so that the rope runs 
through it and drops back soaked with creosote into its position on 
the barrier path. The use of post holes to trap the bug- is just as 
essential with the rope harrier as with the other typi 

The rope barrier costs about the same as the paper fence or ground- 
line i vpc of creosote harrier and can be installed more easily. Where 

a smooth path free l'roni lumps and cracks can be made, it is VQT} 

satisfactory. While it act- somewhat as a physical as well 
chemical barrier, it is not so efficient in this respect as the paper fence, 
for it is easily knocked or blown out of place and, where the ground 

is lumpy or cracked, it does not make good contact with the soil 




Figure in. Renewing creosote <>n paper fence: 
i. Receptacle with a copper tube; /.'. guide 
pron- Boldered Dear end of tube; <'. apply- 
ing creosote to paper fence, i Iowa stat«> 
(cultural Experiment station.) 



HOW TO FIGHT THE CHINCH BUG 1 9 

surface. Under such conditions the rope barrier is little, if any, 
improvement over a ground line of creosote, because its effectiveness 
then depends on whether or not the creosote dripping from the rope 
has formed an unbroken line on the ground beneath it. 

COAL-TAR OR GAS-TAR BARRIER 

A well-known type of barrier is made by pouring a narrow line 
of coal tar or gas tar on a path made by smoothing and packing the 
soil as firmly as possible along the margin of the field to be protected. 
Chinch bugs are repelled by the odor of the tar, and while the tar 
is fresh it also acts as a physical barrier because of its stickiness. Tar 
makes a very effective barrier, but it has to be renewed oftener than 
creosote. Where the proper grade can be obtained cheaply and 
readily, its use is highly practical. Tars from which the creosote 
and cresylic acids have not been distilled should be procured, for 
tars from which these materials have been removed, and also tars 
resulting from the manufacture of water gas. have little or no value 
as chinch bug repellents. Post holes properly dug and maintained 
are also essential to the effective operation of tar barriers. 

BURNING ALONG THE HARRIER NOT RECOMMENDED 

It is possible to kill nearly all the chinch bugs along a barrier by 
naming with a large blowtorch, but this method is not recommended, 
since practically the same result can be attained at much less expense 
by the use of the post-hole traps. Bugs congregating on the outer 
rows of corn may be killed by flaming them with a torch, but in 
nearly every case the plants also will be killed. A better procedure 
is to disk up the ruined portion of the field and plant it to soybeans. 

THE DUSTY-FUKROW BARBIES 

The oldest and most widely tised barrier consists of a dusty furrow 
or -trip around the field to be protected. The furrow type is the 
best and is generally made by plowing a dead furrow, throwing the 
dirt both ways, and then dragging a log or trough of planksback 
and forth in this furrow until the sides and bottom have been worked 
down to a fine dust. Sometimes two parallel furrows are plowed, 
and a double drag is constructed with a raised connection t<. -pan 
the intervening ridge. Both furrows may thus he dragged with 
little more Labor than would be required for a single furrow. Effec- 
tive dust barriers have also been maintained by repeatedly dragging 
a harrow back and forth over , strip of ground aero— the field in 
front of the bugs, thus working up a deep, fine dust mulch in which 
the bugs are buried and killed as they craw] into ii. X,, post holes 
are used with barriers that depend oil a dust mulch lor their effec- 
tivem 

On certain types of >oil. and during <\vy weather, dust barriers 
are very satisfactory. While <\iy they remain impassable to chinch 
\>\\<x< if frequently dragged, and most "of the bugs that fall into them 
arc killed by the drag, the heal of the sun. or the penetration of 
line particles of dust into their breathing tubes. Of course, dust 
harriers are of no value during period- of rain. Often a neavv 



2(j FARMERS' BULLETIN 1780 

shower ruins the dust mulch so that the bugs are able to cross in 
sufficient numbers to destroy 1 or 2 acres of corn before a fresh dust 
can be worked up. Also, in some soils it is impossible to make a dust 
so fine that the chinch bugs cannot crawl through it. Although the 
dust barrier does not require any costly equipment or the expendi- 
ture of money for materials, constant labor is necessary to maintain 
it, and the expense is often greater than for a more dependable and 
efficient creosote or tar barrier. 

BARKIKRS THAT ARE OF LITTLE OR NO VALUE 

A number of suggested chinch bug barriers have proved to be 
practically worthless. Barriers made by planting a narrow strip of 
some legume between the small grain and the corn are of little or no 
value. Cowpeas or soybeans are the legumes most frequently used 
in this way. but the bugs crawl through them about as readily as 
they would pass over the bare ground. It has also been suggested 
that the bugs would feed upon freshly cut cornstalks laid in a con- 
tinuous line along the margin of the grainfield. and would be 
poisoned by this material as it soured. Numerous tests with this type 
of barrier nave shown that it is worthless. Occasionally considerable 
numbers of cast-off skins of the bugs may be found scattered through 
the cornstalks, and these are often mistaken for dead bugs. Close 
examination, however, has failed to show that any chinch bugs are 
killed by this kind of a barrier. 

SPRAYING AND DUSTING WITH INSECTICIDES AS EMERGENCY MEASURES 

Spraying and dusting with insecticides are expensive operations 
and thus far have not been found practical for controlling chinch 
bugs in Large fields of either small grain or corn. They are recom- 
mended only as emergency measures where the bug- have invaded 
small plantings of valuable seed corn. In such cases satisfactory 
results require the use of an efficient knapsack sprayer or duster. 
Since chinch bugs do not eat plant tissue, but \\'(h\ only by piercing 
the stems or leaves with their sharp beaks and sucking the sap. they 
cannot be killed by poison sprayed or dusted on the plains. The 
l.ug- themselves must be hit with a -pray or dust that will kill them 
upon contact. This is usually difficult to do thoroughly, because 
many of them are hidden under leaf sheath- and foliage or are 
moving about on the ground. 

One (1 f the best sprays for this purpose consists of one-half ounce 
of 40-percent nicotine sulphate and 1 ounce of soap, dissolved in 1 
gallon of water. This Bpray will kill all bugs wet with it and is not 
injurious to the corn except when applied so that it accumulates in 
t he heart or curl of the plant. Where this occurs, the soap SOmet imes 
kills the leaves when the water evaporates. Solution- made with 
certain grade- of laundry soap, without the nicotine sulphate, make 
fairly effective -pray.-. With soft water. 3 or 3% ounce- of soap t<> 
;i gallon i- sufficient, hut more is necessary if the water is hard. All 

chinch bug- thoroughly wet with the soap solution will be killed, but 
soap sprays must be used with caution, as they may injure the corn. 



HOW TO FIGHT THE CHINCH BUG 21 

When chinch bugs are congregated on the first rows of corn, dust- 
ing is sometimes more effective than spraying. Less labor is required 
for dusting and, although the material costs more, dusting can often 
be done to better advantage. A few of the bugs on the outer leaves 
of the plant may escape the dust, but nearly all can be killed. A 
2.4-percent nicotine dust is harmless to corn plants, is very effective 
in killing chinch bugs, and may be applied at a fairly rapid rate. It 
is better to buy this dust ready mixed, especially if the quantity 
needed is small. 



UNMENr PNIN ' 



For sale by the Superintendent of Documents, Washington, D. C. .... Price 10 cents 



UNIVERSITY OF FLORIDA 

fllllllllll 

3 1262 09216 4440